1. Field of the Invention
The present invention relates to improvements on a submersible electrical power generating plant. More specifically, my invention is primarily intended for providing an improved electrical power generating plant that is able to generate electricity from the kinetic energy contained in steady ocean currents.
2. Description of the Prior Art
The wealth of the United States has been created largely through the exploitation of cheap energy provided by the past abundance of fossil fuels. Because of the increasing shortages of natural gas in North America and the approaching worldwide shortages of oil, and because of the growing danger of global warming caused by the combustion of fossil fuels, reliable sources of renewable energy are needed.
A growing percentage of the efforts to utilize renewable sources of energy has been concentrated in the creation of wind farms. Although wind powered generating systems should be encouraged, they do have a problem: wind energy is inherently intermittent. Wind speeds can fluctuate hourly and have marked seasonal and diurnal patterns. They also frequently produce the most power when the demand for that power is at its lowest. This is known in the electricity trade as a low capacity factor. Low capacity factors, and still lower dependable on-peak capacity factors, are the major source of wind power""s problem. Because of the steadiness of the Coriolis force driven ocean currents, submersible generators can have capacity factors equal to those of many fossil fuel plants. The fact that these ocean currents can produce a steady supply of electricity, makes that power much more valuable than the intermittent power produced by the wind-driven turbines. For the submersible turbines to achieve the high capacity factors, however, proper placement is very important.
Ocean currents flow at all depths in the ocean, but the strongest usually occur in the upper layer which is shallow compared to the depth of the oceans. The main cause of surface currents in the open ocean is the action of the wind on the sea surface. A wind of high constancy, blowing over great stretches of an ocean, have the greatest effect on producing current. It is for this reason that the north-west and south-east trade winds of the two hemispheres are the mainspring of the ocean""s surface current circulation. In the Atlantic and Pacific oceans the two trade winds drive an immense body of water westwards over a width of some 50 degrees of latitude, broken only by the narrow belt of the east-going Equatorial Counter-current, which is found a few degrees north of the equator in both of these oceans. A similar westward flow of water occurs in the South Indian Ocean, driven by the south-east trade wind. These westward surface currents produce giant eddies that are centered in latitudes of approximately 30xc2x0 N. and S. that rotate clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere. Currents of over 3.5 mph are confined to very restricted regions. They have been recorded in the equatorial regions of the oceans, and in the warm currents flowing to higher latitudes in the western sides of the oceans, with the exception of the Brazil current. The book, Ocean Passages of the World (published by the Hydrographic Department of the British Admiralty, 1950), lists 14 currents that exceed 3 knots (3.45 mph), a few of which are in the open ocean. The Gulf Stream and the Kuro Shio are the only two currents the book lists having velocities above 3 knots that flow throughout the year. Both of these currents are driven by the Coriolis force that is caused by the Earth""s eastward rotation acting upon the ocean currents produced by the trade winds. Because these currents are caused by the Earth""s rotation, they will continue flowing as long as our planet continues to turn on its axis.
The Gulf Stream starts roughly in the area where the Gulf of Mexico narrows to form a channel between Cuba and the Florida Keys. From there the current flows northeast through the Straits of Florida, between the mainland and the Bahamas, flowing at a substantial speed for some 400 miles. It hits its peak velocity off Miami, where the Gulf Stream is about 45 miles wide and 1,500 feet deep. There the current reaches speeds of as much as 6.9 mph in its narrow central axis, which is located less than 18 miles from shore between Key Largo and North Palm Beach. Farther along it is joined by the Antilles Current, coming up from the southeast, and the merging flow, broader and moving more slowly, continues northward and then northeastward, where it roughly parallels the 100-fathom curve as far as Cape Hatteras.
The Kuro Shio is the Pacific Ocean""s equivalent to the Gulf Stream. A large part of the water of the North Equatorial current turns northeastward east of Luzon and passes the east coast of Taiwan to form this current. South of Japan, the Kuro Shio flows in a northeasterly direction, parallel to the Japanese islands, of Kyushu, Shikoku, and Honshu. According to Ocean Passages of the World, the top speed of the Kuro Shio is about the same as that of the Gulf Stream. The Gulf Stream""s top flow rate is 156.5 statute miles per day (6.52 mph) and the Kuro Shio""s is 153 statute miles per day (6.375 mph). Other possible sites for the underwater generators are the East Australian Coast current, which flows at a top rate of 110.47 statute miles per day (4.6 mph), and the Agulhas current off the southern tip of South Africa, which flows at a top rate of 139.2 statute miles per day (5.8 mph). Another possible site for these generators is the Strait of Messina, the narrow opening that separates the island of Sicily from Italy, where the current""s steady counter-clockwise rotation is producedxe2x80x94not by the windxe2x80x94but by changing water densities produced by evaporation in the Mediterranean. Oceanographic current data will suggest other potential sites.
Submersible turbine generating systems can be designed to efficiently produce power from currents flowing as slowly as 3 mphxe2x80x94if that flow rate is consistentxe2x80x94by increasing the size of the turbines in relation to the size of the generators, and by adding more gearing to increase the shaft speeds to the generators. Because the Coriolis currents can be very steady, capacity factors of between 70 percent and 95 percent are possible. This compares to capacity factors for well-located wind machines of between 23 percent and 30 percent. Because a well-placed submersible water turbine will operate in a current having even flow rates, it is possible for them to produce usable current one-hundred percent of the time.
Most water turbines are impulse and reaction turbines, which are very different from those that would be used for these underwater generators. Most water turbines obtain their kinetic energy from a head of water, making them well suited for dam sites. These submersible turbines would obtain no energy from a head of water and could be likened more to a child""s pinwheel that would be powered by water rather than air. Although the turbines on the invention would have more in common with the wind turbines than the impulse and reaction water turbine, there would be major differences. The water would be much denser and would be moving much more slowly.
The amount of kinetic energy contained in a moving fluid can be calculated using the following formula:
KE=xc2xdxc3x97Mxc3x97V2.
M=mass per second
V=velocity
The mass is the weight of the fluid that passes through the diameter of the turbine""s blades per second. This is obtained by calculating the area of the blade""s sweep and multiplying that quantity by the distance the fluid traveled in one second. This volume is then multiplied by the weight of the fluid per cubic unit to get the mass. Because the mass passing through the blades in one second is a factor of the velocity, the power produced by the current does not increase by the square of the velocity, but by its cube. Therefore, the equation for the kinetic energy passing through the turbine can also be written:
KE=xc2xdxc3x97Axc3x97Dxc3x97V3
A=area swept
D=density/cu. m.
V=velocity
Wind turbines that generate electric power usually have two or three long, narrow rotor blades. They have these long bladesxe2x80x94not because they can capture the most kinetic energy from the windxe2x80x94but because the blades must be able to survive violent wind conditions. A wind turbine with many blades or very wide blades would be subject to extremely large forces when the wind blows at hurricane velocities because the energy in the wind increases with the cube of its velocity. To limit the impacts from these extreme conditions, the manufacturers of wind machines prefer that their turbines have only two or three long and narrow rotor blades that can be feathered and locked. Because the underwater turbines would be powered by the relatively steady and comparatively slow movement of a medium that is approximately 870 times the density of airxe2x80x94instead of the water turbines having just two or three narrow blades to absorb the kinetic energy form a small percentage of the fluid passing through the rotor""s sweep areaxe2x80x94the water turbines can have full-bladed rotors with many wide blades that can cover most of their sweep areas. These solid rotors would allow the turbines to extract a larger percentage of the kinetic energy from the fluid passing through the sweep area. The water turbines"" rotor blades would be cupped, with the cups being deeper near the hubs than out at the much faster moving tips. Because there are only small variations in the velocities of the Coriolis-force currents, there would be no need to feather or stop the blades.
Because the kinetic energy increases and decreases with the cube of the fluid""s velocity, a 5 mph current can produce almost twice the power as a 4 mph current, using turbines of the same size. This does not mean that the turbines in the faster currents will always produce the most power per dollar invested because it is possible that turbines in somewhat slower currents near shore can have lower capital costs per kilowatt of generating capacity than those turbines placed in stronger currents much farther offshore. Turbines placed in slower currents will require larger rotors and more gearing to convert the slower turning, higher torque revolutions into the high rotation speeds required by the generators.
The highest operating efficiency obtainable by the narrow-bladed wind turbines under ideal conditions is about 45%. Even though it is possible for the water turbines to have higher efficiencies than 45% because of their full-bladed rotors, the following calculations are based on that efficiency. Assuming efficiencies of 45%, water turbines generating 600 kilowatts of electricity would require rotor diameters as shown in the following table:
To produce the same amount of electric power from low current velocities as from high current velocities, not only are larger rotor diameters required, but also more gearing is required to increase the slower shaft speeds to those high RPMs shaft speeds required by the generators.
One factor that must be addressed when designing any submerged generator that will be tethered with an anchor system is the downward vector force that will be produced by the drag on the downward angled anchor line. The downward vector force increases in the same proportion as does the tangent of the anchor line""s downward angle where the line attaches to the unit. If a unit was prevented from moving lower and the horizontal drag totaled 100,000 pounds, the downward forces and the pounds of pull on the anchor chain would increase as the chain angle increased as follows:
If the downward force is not equalized, the unit will be pulled down to that depth where the angle of the anchor chains"" pull would be reduced enough so that the resulting downward vectored forces would equal the upward forces provided by the unit""s buoyancy and hydrofoils. The forces would then be in equilibrium and the unit would remain at that depthxe2x80x94as long as there were no changes in the current""s velocity or in the demands for electrical power. Increasing either of these would increase the horizontal resistance and cause the unit to sink lower. Because the downward forces increase at an increasing rate as the angle of the downward pull increases, the angle that the anchor chain attaches to the unit should be kept reasonably small. Another reason for keeping the anchor line angle small is that the forces pulling on the anchor line increase with the reciprocal of the cosine (the secant) of the anglexe2x80x94and, as that angle increases, increasing the pull on the anchor chain, the anchor""s holding ability is decreasing.
Most wind turbines use a so-called three-phase asynchronous (cage wound) generator, also called an induction generator to generate alternating current. One reason for choosing this type of generator is that it is very reliable and tends to be comparatively inexpensive. The generator also has some mechanical properties, which are useful, such as generator xe2x80x9cslip,xe2x80x9d and certain overload capability.
To increase the RPMs and reduce the torque to manageable levels, the power from the hubs are transferred in either three or four stages. The first stage consists of a strongly built planetary gear system. A second planetary gear system is either attached to a third planetary gear system or to helical gears, depending on the revolutions and torque of the shaft coming from the first stage. The last stage consists of helical gearsxe2x80x94and, depending on the sizing of the gears in the first two or three stages, a fourth stage of helical gears might be required to increase the shaft speeds to the 1,200 to 1,800 RPMs required by the generators producing the 60 Hz current used in the US.
The generators and rotors can be any size as long as they are matched to each other and to the water velocity. The magnitude of voltage generated is fixed by the speed of the rotors and the number of magnetic lines per pole. The more poles there are, the more lines of magnetic force. This also means that the more poles there are, the slower the revolutions required to produce the same amount of power at the same frequency. The synchronous generator speeds required for electric generators can be calculated using the following formula:
Conventional wind-powered machines have compact generators that have 4 or 6 poles and use a rotor-gearbox-generator drive train. The Lagerway wind machines, made in Australia, use large diameter ring generators with many poles (more than 80) and no gearbox. Rather than using a 4 or 6 pole generator, an adaptation of the Lagerway ring generator can be used to reduce the gearbox requirements. A disadvantage of the Lagerway-type ring generators is that the nacelles"" diameter must be much larger.
Electric generators produce heat. The electric current flowing through the conductors, both in the stator and rotor, produces heat because of the electrical resistance. In addition, heat is generated in the steel of the rotor armature core by the changing of magnetic lines. Although the amount of heat from all the losses in large generators is only about 1 percent of the output, it can it be numerically great. For example, a pair of generators producing 1,200 kW might have a loss of 12 kW, which is equivalent to 40,973 BTU per hour. Therefore, a liquid cooling system is needed to dissipate the heat produced by the generators and gearboxes.
Unlike most power plants, the submersible turbines will continue to spin whether there was a demand for the electricity or not. Because the turbines would operate best under steady loads and their operating costs would be zero, any power produced in excess of that needed by the grid system can be used to create energy in another form that can be stored for later use. This can include the production of hydrogen in facilities on land. The simplest way to obtain hydrogen is to split the water molecule into its basic elements by electrolysis. Feeding a direct current through a salt water electrolyte splits the water molecule into two atoms of hydrogen and one of oxygen, with the hydrogen gas collecting at the negatively charged cathode. Common energy efficiencies for electrolysis of water are at about 65%, but efficiencies of 80% to 85% are possible. The amount of hydrogen that can be produced by this method is directly proportional to the amount of electricity used. Instead of adding more generating capacity to handle the periods of peak demands, we should generate more than enough power from the water turbines"" free energy to cover the peak loads and then add additional loads to fully utilize their generating capacity during periods of low demand. Not only can these submersible turbines eliminate the need for fossil fuels to produce electricity, they can also produce hydrogen to replace still more of the natural gas and petroleum that is being depleted, as well as provide the perfect fuel for fuel cells. Producing the hydrogen would also be beneficial environmentally because its combustion produces only water vapor.
An important consideration concerning the placing of these submersible generating units into service is that they will not be readily accessible for servicing and repair. It is possible for these underwater turbines to be designed to generate power for many years without any servicing. This can be accomplished by eliminating moving parts, by using materials that will not be affected by electrochemical reactions while immersed in a salt-water electrolyte and by electrolysisxe2x80x94and by depending on simplicity and the unchanging laws of physics. In those rare situations where a complex electrical depth control system must be used, reliability can still be achieved by building the proper redundancy into that system.
Most of the prior art for generating electricity from ocean currents can be grouped into a few categories. There are the water wheels and rotating canisters that are mounted on vertical shafts that have V-shaped, cupped or articulated buckets, fins, or flippers to reduce the resistance to the water when the periphery of the wheels are moving toward the current. U.S. patents in this group include U.S. Pat. No. 3,973,864 issued to Atherton, U.S. Pat. No. 4,038,821 issued to Black, U.S. Pat. No. 4,134,710 issued to Atherton, U.S. Pat. No. 4,551,066 issued to Frisz, U.S. Pat. No. 4,748,808 issued to Hill, U.S. Pat. No. 4,818,888 issued to Lenoir, and U.S. Pat. No. 6,006,518 issued to Geary. There are patents for devices having vertical turbines that are mounted on horizontal shafts that do not use shrouds or other devices that surround the rotors. These patents include U.S. Pat. No. 4,023,041 issued to Chappell, U.S. Pat. No. 4,137,005 issued to Comstock and U.S. Pat. No. 5,440,176 issued to Haining. Then there are more U.S. patents that use turbines mounted on horizontal shafts in which the rotors are enclosed in shrouds, flarings, hollow tubes, Venturi-shaped tubes, or have funnel-shaped intakes for the purpose of increasing the water velocity through the turbine. Examples of these include U.S. Pat. No. 3,980,894 issued to Vary, U.S. Pat. No. 3,986,787 issued to Mouton, U.S. Pat. No. 4,095,918 issued to Mouton, U.S. Pat. No. 4,163,904 issued to Skendrovic, U.S. Pat. No. 4,205,943 issued to Vauthier, U.S. Pat. No. 4,306,137 issued to Wracsaricht, U.S. Pat. No. 4,335,319 issued to Mattersheimer, U.S. Pat. No. 4,520,273 issued to Rowe, U.S. Pat. No. 6,064,123 issued to Gislason. Counter-rotating impellers are used in U.S. Pat. No. 4,203,702 issued to Williamson. The blades on these devices overlap and there are V-shaped diverters located ahead of the turbines force the fluid to the outside of the turbines. All the inventions mentioned above are devices that are mounted on underwater structures or are suspended from barges, pontoons, or platforms on pylons at the surface. The problem with mounting the generating devices on platforms is that the strongest currents are near the surface where the depths are usually greater than 1,200 feet and mounting the generating devices high above the ocean floor on giant structures would be extremely costly. The problem with suspending them from barges or pontoons is that they would interfere with ship traffic, be vulnerable to violent storms, and be unsightly.
Among the patented inventions to generate electricity from ocean currents, there are tethered devices that rely on hydrofoils and/or ballast tanks to provide lifting forces to keep the devices at the desired depths. U.S. Pat. No. 6,091,161 issued to Delhsen uses variable-pitch rotor blades to limit the drag force. Although this patent may have things in common with my invention in that they are both tethered and have counter-rotating, rear-facing turbines, the inventions are very different. The Delhsen""s submersible underwater generating device would have little or no stability because, with the buoyancy tank between the heavy elements and not above them, its center of buoyancy is not above the center of gravity. Also the lifting force provided by the hydrofoil that joins the nacelles is at the same level as the heavy elements, further adding to a lack of stability. The upward canted hydrofoil wing tips that supposedly provide roll stability would have little or no effect unless the hitch points to the two anchor lines were lower. Because the anchor lines attach directly ahead of the center of drag, the canted wing tips would have little effect on stability. The resistance to roll is further decreased in the Delhsen invention by the anchor line""s attachment point being at the same height as the center of buoyancy rather than below it. With the attachment point located there, if the device should have positive buoyancy, the canted wing tips would decrease stability. The placement of the stabilizer fin forward of the hydrofoil makes no sense. With the anchor attachment points being behind this xe2x80x9cstabilizing fin,xe2x80x9d the fin would make the device more unstable. The device uses two anchors, each connected to capstans that are located at the front of each nacelle to adjust the anchor chains to eliminate yaw. The hydrofoil between the nacelles contains separate ballast tank compartments that are capable of being filled with fluid or purged to control buoyancy and the shift the center of buoyancy. The nacelles also contain buoyancy tanks that can be independently filled or purged to compensate for roll of the device. The Delhsen invention utilizes a computer system to balance those forces produced by the hydrofoil, buoyancy and drag to allow the device to seek that current that will allow for an even production of electric power. The drag force on the rotors is controlled by adjusting the pitch of the rotor blades so that the device seeks an initial equilibrium velocity of water current that will allow the tethered device to stay within a chosen predetermined depth range. A problem with this approach is that, although the purpose of the generator is to capture kinetic energy to maximize power output, it controls the depth by reducing that output.
U.S. Pat. No. 6,109,863 issued to Milliken is another tethered unit that consists of a buoyant device that contains two counter-rotating water wheels or turbines that are mounted side-by-side on vertical shafts. The vanes of the turbine have sub-vanes that open when the large vanes are moving toward the current to allow the water to pass through them. Although these are counter-rotating turbines that are side-by-side, because they are mounted on vertical shafts, their counter rotation has no effect on the device""s stability. In this and all other devices that use turbines mounted on vertical shaftsxe2x80x94not only are the areas for capturing the energy of the moving fluid small in proportion to the frontal area of the device, they waste additional energy becausexe2x80x94even though the fins on the reverse side of the vertical turbine may fold or open to allow water to have much less resistance as they rotate toward the front of the turbinexe2x80x94they still produce some drag that must be subtracted from the power produced by that side of the turbine that is being pushed by the kinetic energy of the flowing water. The inefficiencies of all these vertical shafted turbines can be compared to using paddle wheels for propelling boats rather than modern propellers. Also the invention has no means of balancing changing downward vector forces that would result from changes in drag, caused by changes in either the current velocity or changes in the generator loads acting on the downward angled anchor line.
U.S. Pat. No. 4,219,303 issued to Mouton is a tethered unit with a pair of axle-less, counter-rotating, co-axial turbine wheels having ring rims that bear against friction drive wheels which turn one or more electrical generators that are contained in water-tight rooms within the wall of a nozzle or shroud that surround the periphery of the turbines. To increase the velocity of the water through the turbines, the device has an opening nozzle in the front that directs the water into a narrowing vena contracta, through the two counter-rotating, co-axial turbines and then on to an expanding shroud downstream that is for the purpose of increasing the water""s velocity. This device depends on buoyancy and a weight on the bottom to maintain the proper depth. Many devices use vertical turbines mounted radially on horizontal shafts that are enclosed in shrouds, hollow tubes, Venturi-shaped tubes, or have funnel-shaped intakes to increase the fluid velocity through the turbines. Although it is possible for the velocity of the fluid passing through a vertical turbine""s sweep area to be increased somewhat by using these devices, much of the kinetic energy contained in additional cross-section of the moving fluid is absorbed by those shrouds and funnel shaped devices in the form of increased frontal resistance (drag) that slows the water flow to offset some of the accelerated flow being channeled through the smaller constricted area of the turbine. Shrouds and Venturi-shaped tubes are not used on commercial wind-powered turbines because they do not increase the velocities enough to justify their cost. Instead of using these devices, the manufacturers of the wind machines increase the diameters of the turbine rotors. This is also the best approach for the water turbines.
A key consideration when designing a tethered submersible generator is that of stability. A fully submerged object that is floating freely in a liquid will always float with its center of buoyancy (the center of gravity of the fluid that the object is displacing) directly above the object""s center of gravity. The prior art does not show tethered submersible electrical power plants that utilized this principal of physics.
Although previous inventions may also generate electric power with low operating costs, none can produce as much power at such low cost per kilowatt hour as my invention because of its highly efficient energy-collecting design and its extremely low maintenance requirements.
Accordingly, it is a principal object of my invention to provide a submersible electrical power generating plant that is capable of being free of service or replacement for many years.
It is a further object of my invention to provide a stable submersible electrical power generating plant that has its center of buoyancy located above its center of gravity.
It is a still further object of my invention to provide a submersible electrical power generating plant that has an adjustable center of gravity.
It is a further object of my invention to provide a submersible electrical power generating plant that is capable of generating electrical power from low speed current flow when equipped with turbines, generators, and gearing are properly sized for the slow current.
It is a still further object of my invention to provide a submersible electrical power generating plant that is made of carbon fiber composites.
It is a further object of my invention to provide a submersible electrical power generating plant that has improved directional stability.
It is a further object of my invention to utilize the same changes in the current""s kinetic energy that changes the downward vector forces to adjust the lifting forces to balance those downward forces.
It is a further object of my invention to utilize those unchanging lifting forces produced by displacement to support the unchanging weight of the submersible electrical power generating plant, and to utilize those changing lifting forces that are produced by the hydrofoils to balance the changing downward vector forces.
Other objects of my invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or apparent from, the following description and the accompanying drawing figures.
According to my present invention I have provided a submersible electrical power generating plant for generating electrical power with no fuel costs from the flow of ocean current.
In the present invention, a submersible electrical power generating plant for generating electrical power with almost no operating costs from the flow of ocean current has a submersible electrical power generating structure and an electrical power collection and transmission structure connected to the submersible electrical power generating structure for collecting and transmitting electrical current.
The submersible electrical power generating structure, made of carbon fiber composites, has a superior located center of buoyancy (the center of gravity of that water being displaced), an inferior located center of gravity and a center of drag (that point where sum of all the drag forces caused by every exposed part of an object moving through a fluid are balanced). The power generating structure has a streamlined torpedo-shaped buoyancy tank with a nose end, a rear end, a top side, a bottom side, a left side, a right side, a plurality of valves and a plurality of compartments. Said center of gravity of said submersible electrical power generating structure can be changed by adding water into or subtracting water from said streamlined torpedo-shaped buoyancy tank. The streamlined torpedo-shaped buoyancy tank has a vertical tail fin capable of improving directional stability of said submersible electrical power generating structure. Said vertical tail fin can be on either said top side of said submersible electrical power generating structure extending upward or said bottom side of said submersible electrical power generating structure extending downward. The water level in each of said plurality of compartments is adjustable by piping the water in and out through said plurality of valves. The power generating structure has a pair of side-by-side counter-rotating water turbine rotors. Said water turbine rotors are full-bladed, having wide rotor blades that cover most of the turbines"" sweep area. Said pair of side-by-side counter-rotating full-bladed water turbine rotors are made of carbon fiber composites and sufficiently hollow so that their density is near that of the water that is displaced by said pair of side-by-side counter-rotating full-bladed water turbine rotors. Said pair of side-by-side counter-rotating full-bladed water turbine rotors turn so that both said plurality of first blades and said plurality of second blades are moving downward at the center of the submersible electrical power generating plant and upward on the outside of the submersible electrical power generating plant. One of said pair of side-by-side counter-rotating full-bladed water turbine rotors is a mirror image of said second water turbine rotor. Each of said pair of side-by-side counter-rotating full-bladed water turbine rotors has a horizontal water turbine axis parallel to said streamlined torpedo-shaped buoyancy tank. Each of said pair of side-by-side counter-rotating full-bladed water turbine rotors has a plurality of rotor blades, which extend radially outward from said horizontal water turbine axis. Said pair of counter-rotating full-bladed water turbine rotors are located beneath said streamlined torpedo-shaped buoyancy tank and facing rear end of said streamlined torpedo-shaped buoyancy tank. The power generating structure has a pair of watertight nacelles. Each of said pair of watertight nacelles is connected to one of said pair of horizontal water turbine axis. Said pair of watertight nacelles is firmly connected to each other through a center connecting means, which has an upside, a down side and a center point. The center point is located slightly forward of and below said center of drag of said submersible electrical power generating structure. Said center connecting means being securely mounted to said bottom side of said streamlined torpedo-shaped buoyancy tank through a third connecting means, which is long enough to ensure said submersible electrical power generating structure having said center of buoyancy above said center of gravity. Said pair of watertight nacelles are securely mounted to said bottom side of said streamlined torpedo-shaped buoyancy tank. Each of said pair of watertight nacelles has a low-speed shaft connecting to said horizontal water turbine axis, a gear box connecting to said low-speed shaft capable of converting low speed to high speed, a high-speed shaft connecting to said gear box, and an electrical power generator driven by said high speed shaft capable of generating electrical power. Said pair of watertight nacelles are located sufficiently far apart to provide clearance for said pair of side-by-side counter-rotating full-bladed water turbine rotors. Said center connecting means has a cooling system capable of effectively and efficiently distributing heat generated by said gear boxes and said electrical power generators to outside water.
To maintain a uniform depth, increases in the downward vector force that are caused by increased drag must be balanced by an equal and opposite lifting force. Those lifting forces that are produced by displacement are not affected by current velocity and are used primarily to provide some positive buoyancy to the submersible generator. Those lifting forces that are produced by the flow of a fluid over an airfoil-shaped hydrofoil are affected by current velocity, and these lifting forces are utilized to balance the changing downward forces by changing the hydrofoil""s angle of attack. The angle of attack is increased by raising the front edge of the hydrofoil higher than the back edge of the hydrofoil in relation to the flow of the water. With the vertical height of the anchor line attachment point properly adjusted on a strong bar (which acts as a lever), increased dragxe2x80x94which will increase the downward vector forcexe2x80x94will provide the proper leverage to that bar to cause the increased pull on the anchor line to cause the entire submersible power plant to rotate vertically (raising the nose and dropping the trail) so that the hydrofoils increasing angle of attack will provide only that additional lifting force required to balance the increased downward vector forcexe2x80x94thereby allowing the submersible generating plant to remain at a reasonably uniform depth.
It should be further noted that because the exterior surface of the present invention will not corrode and because the present invention relies on the unchanging laws of physics and mechanical simplicity, it is capable of operating for between 8 and 20 years without servicing or replacement. The primary reason that the present invention would need to be brought out of the water for servicing is because of bio-fouling or biological growth of organisms on the exterior surfaces. For example, the hulls of ocean-going ships are often coated with anti-fouling paints that can keep the bio-organism growth under control for about 5 years. The reason that these organisms must be removed from ships is that their growth increases the drag of the hull moving through the water, reducing speed and increasing fuel consumption. Furthermore, a large build-up of bio-organisms can also make it difficult for ships to navigate.
Because the submersible turbines burn no fuel and do not navigate, a large build-up of bio-growth should have little or no effect on the present invention""s efficiency. Only when the turbine blades acquire so much growth that they lose efficiency, will cleaning be necessary. The exterior surface of the present invention should be coated with a heavy coating of an anti-fouling paint before it is placed into service. With the proper antifouling coating, the present invention should operate without need for service or cleaning for at least 8 years, and a period of more than 20 years is possible. In this regard, the submersible electrical power generating plant is capable of being free of service or replacement for many years. It is neither mounted on underwater structures nor suspended from any structure at water surface. It is capable of generating electrical power from low speed current flow when equipped with larger turbines and/or smaller generators and more gearing. It is also capable of conveying kinetic energy by said pair of side-by-side counter-rotating full-bladed water turbine rotors through said pair of electrical power generators.
In a preferred embodiment, the power generating structure has an attaching device located at said center point of said center connecting means. The attaching device being adjustable up and down vertically by a device that may be powered by electricity or compressed air. With the vertical height of said attachment device properly adjusted at a point below and slightly forward of the submersible electrical power generating plant""s center of drag, increases in the drag force will cause the submersible electrical power generating plant to rotate vertically which will increase the angle of attack of the airfoil-shaped hydrofoils by lifting the leading edge of the hydrofoil higher than the trailing edge in relation to the flow of water to increase the lifting force to balance the increased downward vector force caused by the increased drag acting through the downward angled anchor line.
The streamlined torpedo-shaped buoyancy tank has a pair of airfoil-shaped hydrofoils. One of said pair of airfoil-shaped hydrofoils is a mirror image of the other. One airfoil-shaped hydrofoils is fixed on said left side of said streamlined torpedo-shaped buoyancy tank projecting horizontally leftward. The other airfoil-shaped hydrofoil fixed on said right side of said streamlined torpedo-shaped buoyancy tank projecting horizontally rightward. Said pair of airfoil-shaped hydrofoils are located at said rear end of said streamlined torpedo-shaped buoyancy tank, which are capable of providing increasing lift while countering an increasing vertical rotational force that would result from an increasing drag acting on said anchor line""s attachment point that is below said center of drag. Said pair of airfoil-shaped hydrofoils is capable of providing said submersible electrical power generating plant with equal and opposite lifting forces to balance changing downward vector forces with a depth-control system that uses no moving parts to keep said submersible electrical power plant at a uniform depth. The water level in each of said plurality of compartments is adjustable by piping the water in and out through said plurality of valves to make longitudinal adjustments of the center of gravity.
There is a weight member on ocean floor connecting to said submersible electrical power generating structure through a connecting means at said attaching device. Said weight member on ocean floor limiting the height of said submersible electrical power generating structure floating above the ocean floor.
In a second embodiment, the streamlined torpedo-shaped buoyancy tank has two pairs of airfoil-shaped hydrofoils instead of one pair. This is the only difference between the first embodiment and the second embodiment. One of the first pair of airfoil-shaped hydrofoils is a mirror image of the other. One of the first pair of airfoil-shaped hydrofoils is fixed on said left side of said streamlined torpedo-shaped buoyancy tank projecting horizontally leftward and the other is fixed on said right side of said streamlined torpedo-shaped buoyancy tank projecting horizontally rightward. Said first pair of airfoil-shaped hydrofoils located above said center of gravity of said submersible electrical power generating structure. The second pair of airfoil-shaped hydrofoils is located at rear end of the streamlined torpedo-shaped buoyancy tank. One of said second pair of airfoil-shaped hydrofoils is a mirror image of the other. One of said second pair of airfoil-shaped hydrofoils is fixed on said left side of said streamlined torpedo-shaped buoyancy tank projecting horizontally leftward and the other is fixed on said right side of said streamlined torpedo-shaped buoyancy tank projecting horizontally rightward. Both said first pair of airfoil-shaped hydrofoils and said second pair of airfoil-shaped hydrofoils are capable of providing said submersible electrical power generating structure with more lift and less drag at high angle of attack. Both said first pair of airfoil-shaped hydrofoils and said second pair of airfoil-shaped hydrofoils are capable of providing said submersible electrical power generating plant with equal and opposite lifting forces to balance changing downward vector forces with a depth-control system that uses no moving parts to keep said submersible electrical power plant at a uniform depth.
In a third embodiment, said center connecting means in the preferred embodiment has a horizontal level arm at said center point of said center connecting means extending horizontally backward toward said rear end of said streamlined torpedo-shaped buoyancy tank. Said horizontal level arm has another pair of horizontal fins. One horizontal fin is a mirror image of another horizontal fin. Said horizontal level arm and said pair of horizontal fins have a specific gravity near that of the water they are placed in. The horizontal level arm and the pair of horizontal fins are capable of keeping said pair of side-by-side counter-rotating full-bladed water turbine rotors facing directly into the current regardless of the nose-high attitude or position of the streamlined torpedo-shaped buoyancy tank.
In a fourth embodiment, the streamlined torpedo-shaped buoyancy tank has two pair of fins as those in the second embodiment. However, the first pair of fins has been modified. The first pair of airfoil-shaped hydrofoils has a first airfoil-shaped hydrofoil and a second airfoil-shaped hydrofoil. Said first airfoil-shaped hydrofoil has a first leading edge. Said second airfoil-shaped hydrofoil has a second leading edge. Both of said first pair of airfoil-shaped hydrofoils are self-adjusting lifting hydrofoils. Said first airfoil-shaped hydrofoil is a mirror image of said second airfoil-shaped hydrofoil. Said first airfoil-shaped hydrofoil is fixed on said left side of said streamlined torpedo-shaped buoyancy tank at a first pivoting point through a first pivoting member projecting horizontally leftward. A first front surface area of said first airfoil-shaped hydrofoil front of said first pivoting member is nearly equal to a first back surface area of said first airfoil-shaped hydrofoil behind said first pivoting member. Said first airfoil-shaped hydrofoil has a first lever arm. Said first lever arm attached to said first airfoil-shaped hydrofoil at said first pivoting point and extending vertically upward. Said first lever arm has a first flat plate. Said first flat plate is capable of being slid up and down said first lever arm and secured at any point. Said first airfoil-shaped hydrofoil has a first rod at said first leading edge. Said first rod extends forward has a first counter weight, which is capable of being secured at any point on said first rod. Said first leading edge is prevented from tipping below horizontal or any angle by said first adjustable stop. The second airfoil-shaped hydrofoil fixed on said right side of said streamlined torpedo-shaped buoyancy tank at a second pivoting point through a second pivoting member projecting horizontally rightward and has the same structure and features of said first airfoil-shaped hydrofoil. Said first airfoil-shaped hydrofoil and said second airfoil-shaped hydrofoil are linked together by a shaft extending horizontally through said streamlined torpedo-shaped buoyancy tank at both said first pivoting point and said second pivoting point. Said first pair of airfoil-shaped hydrofoils is located above or slightly forward of said center of gravity of said submersible electrical power generating structure. Said first pair of self-adjusting airfoil-shaped hydrofoils is capable of automatically adjusting the lifting force of said first pair of self-adjusting airfoil-shaped hydrofoils to balance changes in the downward force caused by changes in current velocity.